android RecyclerView Add footerview Detailed explanation

class FooterViewAdapter :&lt;&gt;() {

    companion object {
        const val TYPE_FOOTER: Int = 1
        const val TYPE_NORMAL: Int = 0
    }

    var isFooterView: Boolean = false

    fun setFooterView() {
         = true
        notifyItemInserted(itemCount)
    }

    fun removeFooterView() {
         = false
    }


    override fun getItemViewType(position: Int): Int {
        return if (isFooterView &amp;&amp; position == itemCount - 1) TYPE_FOOTER else TYPE_NORMAL
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int):  {
        if (viewType == TYPE_FOOTER) {
            val view = ()
                .inflate(.focus_footer_view_no_line, parent, false)
            return BottomViewHolder(view)
        }
        
        return Other settingsVIewHolder
    }


    override fun onBindViewHolder(holder: , position: Int) {
        if (getItemViewType(position) == TYPE_FOOTER) return
        Your binding event does not need to be moved
    }
    class BottomViewHolder(view: View) : (view) {
    }
    
    override fun getItemCount(): Int {
        return if (isFooterView &amp;&amp;  &gt; 0)  + 1
        else 
    }
}

1. Define the type of viewtype, one is normal and the other is the bottom view

 companion object {
        const val TYPE_FOOTER: Int = 1
        const val TYPE_NORMAL: Int = 0
    }

2.Define whether to add aFooterViewofBooleanvariable
（1）如果你of底部view是固定of，No need to parse multiple timesxmllayout，Directly inonCreateViewHolder方法里解析一次layout。
var isFooterView: Boolean = false
（2）如果你of底部layout是变化of，那这里设置of就应该是
var isFooterView: View

Related Methods

//Set FooterViewfun setFooterView() {
         = true
        notifyItemInserted(itemCount)
       //This method is to notify Adapter that there is a new Item insertion    }

//Remove FooterView    fun removeFooterView() {
         = false
    }

4. Rewrite getItemViewType
According to isFooterView, determine whether the FooterView&&item is the last one to locate the last one. The other ViewTypes are TYPE_NORMAL

override fun getItemViewType(position: Int): Int {
        return if (isFooterView && position == itemCount - 1) TYPE_FOOTER else TYPE_NORMAL
    }

This method is very important, it is to calculate how many Items there are, and it is also used above.
It's very simple, add FooterView, add 1 for ItemCount

override fun getItemCount(): Int {
        return if (isFooterView &&  > 0)  + 1
        else 
    }

6. Next create an empty ViewHolder, of course, you can reuse other created ViewHolders

 class BottomViewHolder(view: View) : (view) {
    }

7. Rewrite onCreateViewHolder and parse different layouts according to viewType.

 override fun onCreateViewHolder(parent: ViewGroup, viewType: Int):  {
        if (viewType == TYPE_FOOTER) {
            val view = ()
                .inflate(.focus_footer_view_no_line, parent, false)
            return BottomViewHolder(view)
        }
        
        return Other settingsVIewHolder
    }

8. Rewrite onBindViewHolder, and skip it if viewType is TYPE_FOOTER

 override fun onBindViewHolder(holder: , position: Int) {
        if (getItemViewType(position) == TYPE_FOOTER) return
        Your binding event does not need to be moved
    }

9. Finally, let’s talk about getAdapterPosition and getLayoutPosition
The suggestions are as follows:

When you need to bind data, use(); to get it in real time

When you click/slide and other monitoring events, use (); to get the location

Most of the time, there is no difference between() and(), because the difference in data between the two is within 16ms

Summarize

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